Energy Exchange Control in Multiple Microgrids with Transactive Energy Management

In recent years,the advent of microgrids with numerous renewable energy sources has created some fundamental challenges in the control,coordination,and management of energy trading between microgrids and the power grid.To respond to these challenges,some techniques such as the transactive energy(TE)technology are proposed to control energy sharing.Therefore,this paper uses TE technology for energy exchange control among the microgrids,and applies three operation cases for analyzing the energy trading control of four and ten microgrids with the aim of minimizing the energy cost of each microgrid,respectively.In this regard,Monte Carlo simulation and fast forward selection(FFS)methods are respectively exerted for scenario generation and reduction in uncertainty modeling process.The first case is assumed that all microgrids can only receive energy from the network and do not have any connection with each other.In order to maximize the energy cost saving of each microgrid,the second case is proposed to provide a positive percentage of cost saving for microgrids.All microgrids can also trade energy with each other to get the most benefit by reducing the dependency on the main grid.The third case is similar to the second case,but its target is to indicate the scalability of the models based on the proposed TE technology by considering ten commercial microgrids.Finally,the simulation results indicate that microgrids can achieve the positive amount of cost saving in the second and third cases.In addition,the total energy cost of microgrids has been reduced in comparison with the first case.

Lighting preferences in office spaces concerning the indoor thermal environment

The accurate prediction of the visual comfort zone in an indoor environment is difficult as it depends on many parameters.This is especially the case for large compact urban areas in which the density and shadow from neighboring buildings can limit the accessible daylighting in indoor spaces.This paper investigates the satisfaction range for illuminance regarding indoor air temperature in office buildings and the significant parameters affecting this range in six office buildings in Tehran,Iran.Lighting comfort has been evaluated by a subjective survey(509 total responses)and field measurement.The questionnaires were filled out in 146 and 109 rooms in summer and winter,respectively.The results show that the illuminance should not be less than 550 lx,while illuminance between 600 and 650 lx provides the highest satisfaction level.The satisfaction with lighting level is affected by individual parameters such as age,type of activity,and environmental parameters such as window orientation,external obscurations,and season.A relationship was observed between lighting level satisfaction and thermal condition acceptance,and the overall comfort depends more on thermal conditions than the lighting level.

Evaluating the different boundary conditions to simulate airflow and heat transfer in Double-Skin Facade

The CFD simulation accuracy mostly depends on the appropriate setting of boundary conditions and numerical simulation parameters.This study shows the influence of two types of boundary condition settings on the CFD simulation results of Double-Skin Facade(DSF)for a specific problem.These two boundary settings are the constant temperature on the DSF surfaces called Boundary A,and Boundary B is defined via solar radiation using the Discrete Ordinate radiation Model(DOM).The paper verified both the numerical simulations using the experimental data.Comparing the numerical results of two types of boundaries with experimental data shows that both cases underestimated the values lower than 5.2 K and 0.1 m/s for the temperature and velocity respectively at the regarded measured points.Boundary A gives more accurate temperature prediction results,while Boundary B shows velocity magnitude closer to the measurements in the middle height of the cavity;the average temperature and velocity differences between the two boundary types are 0.6 K and 0.003 m/s respectively which are negligible.Finally,the selection of boundary conditions depends on study purposes,however,when the DSF is equipped with blinds and if there is not enough data in hand but the exact value of solar irradiation,using the Boundary B approach is suggested;it can provide reasonable results associated with multi-type of thermal boundary conditions at the same time.Furthermore,if the goal is to investigate the flow pattern in the DSF,Boundary B is argued to perform better than the constant temperature boundary condition.